CSIRO Publishing blank image blank image blank image blank imageBooksblank image blank image blank image blank imageJournalsblank image blank image blank image blank imageAbout Usblank image blank image blank image blank imageShopping Cartblank image blank image blank image You are here: Journals > Marine & Freshwater Research   
Marine & Freshwater Research
Journal Banner
  Advances in the Aquatic Sciences
blank image Search
blank image blank image
blank image
  Advanced Search

Journal Home
About the Journal
Editorial Structure
Online Early
Current Issue
Just Accepted
All Issues
Special Issues
Research Fronts
Virtual Issues
Sample Issue
For Authors
General Information
Submit Article
Author Instructions
Open Access
For Referees
General Information
Review an Article
Referee Guidelines
Annual Referee Index
For Subscribers
Subscription Prices
Customer Service
Print Publication Dates

blue arrow e-Alerts
blank image
Subscribe to our Email Alert or RSS feeds for the latest journal papers.

red arrow Connect with us
blank image
facebook twitter LinkedIn


Article << Previous     |     Next >>   Contents Vol 56(4)

Spatial and temporal variability of nitrogen dynamics in an upland stream before and after a drought

D. S. Baldwin A B, G. N. Rees A, A. M. Mitchell A, G. Watson A

A Murray–Darling Freshwater Research Centre and the CRC for Freshwater Ecology, PO Box 991, Wodonga, Vic. 3689, Australia.
B Corresponding author. Email: darren.baldwin@csiro.au
PDF (194 KB) $25
 Export Citation


In the current study, we explore the spatial and temporal variability of ammonia, nitrate and urea dynamics in an upland stream before and after a major drying event, using short-term nitrogen additions to benthic chambers. The potential for an initial flush of mineral nitrogen from re-wetted sediments following a prolonged period of drying was also assessed. The distribution of dissolved nitrogen species at four sites spaced along a 1-km reach of the stream were quite variable over time but, in general, not between sites. Conversely, sediment nitrogen dynamics were spatially variable. For example, in one instance, sediments from the uppermost site were a net sink for ammonia, whereas the sediments immediately downstream (separated from the first site by a small sand bar) were a net source of ammonia; with measured sediment fluxes up to ~2 µg N m-2 s-1. In general, the short-term addition of nitrate, ammonia or urea did not substantially affect the sediment nitrogen dynamics. After ~3 months of in situ drying, upon re-wetting, the sediments from all sites immediately produced pulses of ammonia, nitrate and, to a substantially lesser extent, urea. The rates of release of nitrogen were spatially variable, with up to an order of magnitude difference in the rate of release of ammonia from re-wetted sediments from the same small pool. Some differences were observed between nitrogen dynamics before and after drying but a causal linkage could not be established.

Keywords: nitrogen cycling, sediments, spatial heterogeneity.

Subscriber Login

Legal & Privacy | Contact Us | Help


© CSIRO 1996-2015